editable-text-column-mixin

A non-instantiable class that can be mixed with the grid-column class to create grid
columns whose cells act like multi-line-editable-text controls.
Each cell in the column will implement the pseudo-control if the row
of that cell is an instance of a grid-row subclass that mixes in the
widget-row-mixin
class.

To ensure that this mixin class' methods take precedence over other
methods that specialize on grid-column, this mixin class generally should
appear first in a defclass
expression's list of superclasses, as in:

The edit-start-trigger and edit-end-trigger
properties of the column may be used to determine what gesture the
user must make to initiate and complete the typing-in of a new value
for the cell. The user may press either the spacebar or the enter key
to emulate clicking on a cell in this column, and so that will
initiate type-in in the same cases that clicking will. This type
of column may also be given a template-string to restrict what the user may
enter. The scrollbars
property determines whether a vertical scrollbar will appear during
editing; when true (the default) a scrollbar will appear, and when
nil it will not appear (to save space in the
cell).

When the user initiates type-in according to the edit-start-trigger property, the
user is allowed to edit the string displayed in the cell. The user
may then either press the escape key to cancel the edit, or accept the
edit by pressing the enter key or by moving the keyboard focus out of
the cell. If the edit is accepted and the text has changed, then the
column's data-write-converter function is
called to convert the typed string to a meaningful data object, which
is then written by calling write-cell-value.

The read-cell-value method supplied by
this mixin calls the column's data-read-converter to convert the
actual domain data value represented by this cell into a string to be
drawn in the cell. This string is also the initial string to be
edited when the user initiates type-in.

See the section Built-In Grid Cell Widgets on the page for the
grid-widget class for an
overview of the grid column mixins.